international electron devices meeting 2010 summary and outlook walter snoeys – ph ese me – 2011...
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International Electron Devices Meeting 2010
Summary and Outlook
Walter Snoeys – PH ESE ME – 2011 1
Some numbers ~1470 participants (about same level as 2009) 210 regular papers in 33 sessions over 3 days (somewhat less
in number) 555 papers submitted Paper acceptance rate = 35%
(acceptance of university papers low) Growing areas: design-device, packaging/3D, power devices,
energy solar…, bio 2 short courses:
15nm CMOS technology Reliability and Yield of advanced integrated technologies
Luncheon address J. Clifford (Qualcomm) : Evolution and Directions for Mobile Wireless Devices
Evening Panel Sessions: integration + power crunchWalter Snoeys – PH ESE ME – 2011 2
OUTLINE
CMOS
Lithography
Special devices
Metallization
Memories
Displays, Sensors and MEMS
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CMOS in N-well technology
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N+N+P+ N+
N-well
P+ P+
B SS DDG
P-substrate
NMOS
BS
G
D
or G
D
BS
BS
G
D
B
G
D
SPMOS
The ‘real thing’
Mukesh Khare IBM
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Walter Snoeys – PH ESE ME – 2011 6
The real
thing
The MOS transistor: operation principle
Linear region (low Vds)
Electrons are attracted to SiO2-Si interface => conductive layer (channel) is created. (P-substrate gets inverted locally). The channel which links source and drain and forms a resistor between the two. Current increases significantly with increasing VDS
Walter Snoeys – PH ESE ME – 2011 7
n+ n+
SG
D
- - - -
The MOS transistor: operation principle
Saturation region (high Vds)
Significant current flow and resistive drop in the channel. Electrons near the drain are insufficiently attracted by the gate, and the channel gets pinched off. Beyond that point increasing VDS does not change current significantly.
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n+ n+
SG
D
Depletion layer
Note: before inversion layer is formed already current flow = weak inversion
Some examples of MOS characteristics
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Id=f(Vg) Linear scale
0.00E+002.00E-044.00E-046.00E-048.00E-041.00E-031.20E-031.40E-031.60E-03
-0.4
0
-0.1
0
0.2
0
0.5
0
0.8
0
1.1
0
1.4
0
1.7
0
2.0
0
2.3
0
Log(Id)=f(Vg) (Logarithmic scale)
1.00E-13
1.00E-11
1.00E-09
1.00E-07
1.00E-05
1.00E-03
1.00E-01
-0.40 0.05 0.50 0.95 1.40 1.85 2.30
Id=f(Vd)
0.00E+00
5.00E-06
1.00E-05
1.50E-05
2.00E-05
2.50E-05
3.00E-05
0.00 0.35 0.70 1.05 1.40 1.75 2.10 2.45
gm=f(Vg) (in linear regime)
0.00E+00
2.00E-05
4.00E-05
6.00E-05
8.00E-05
1.00E-04
1.20E-04
-0.35 0.10 0.55 1.00 1.45 1.90 2.35
The Boltzmann tyranny
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Log(Id)=f(Vg) (Logarithmic scale)
1.00E-13
1.00E-11
1.00E-09
1.00E-07
1.00E-05
1.00E-03
1.00E-01
-0.40 0.05 0.50 0.95 1.40 1.85 2.30
Ion
Ioff
Exp( )nkT/qVgs
Weak inversion
Strong inversion
Weak inversion slope ~ 60 mV/decade, Ion/Ioff=10e6 => 360 mV
Steep-slope devices (see session 16)
Tunneling (only over limited range) Floating body (hysteresis ! Potential in memories) Polarization in gate dielectric stack
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still really in development
Moore’s law‘The number of transistors per integrated circuit increases exponentially with time
(doubling roughly every two years)’
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More Moore and More Than Moore
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Walter Snoeys – PH ESE ME – 2011 14
More Moore and More Than Moore
How has Moore’s law been possible ?
How has Moore’s law been possible ?
K. De Meyer
K. De Meyer
Mobility enhancement (K. Kuhn) New materials (III-V) and Ge
High mobility but not in all valleys of the band, need to confine carriers to high mobility valley
Low Eg materials (eg Ge) can have higher Ioff due to band-to-band tunneling
Technological challenge: lattice mismatch and defect-free material growth on Si
Different orientations (no strain) On (100) PMOS best <100>, NMOS isotropic On (110) NMOS best <100>, PMOS best <110> Overall best : NMOS (100)<110>, PMOS (110) <110> Hetero Orientation Transistors (HOT)
Stress and Strain : apply strain to channel to change the energy band shape Reduce scattering Enhance mobility, reduce effective mass Pushing carriers in valleys with low effective mass,
Confinement
2008 Krishnamohan et al (session 36.5) PMOS
IEDM 2008 P. Packan et al. (Intel) Session 3.4
Stress improves PMOS and NMOS, but orientation change degrades NMOSConfinement limits this degradation -> Modeling ???
IEDM 2008 P. Packan et al. (Intel) Session 3.4
Confinement limits NMOS degradation -> Modeling ???
Lg = 160 nmReduction 40 %
Lg = 35 nmReduction 13 %
Note: also dependence on W…
‘Planar’ transistors (K. Kuhn)
Walter Snoeys – PH ESE ME – 2011 23Advanced spacer engineering for Cfringe: low k or removal
Going to 15 nm…
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M. Khare
Running out of steam in Bulk
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M. Khare
Reality more difficult than ITRS predictions
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Walter Snoeys – PH ESE ME – 2011 27
Reality more difficult than ITRS predictions
Orthogonal change in roadmap (T. Skotnicki)
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2009 ITRS Roadmap adjustments (T. Skotnicki)
Gate length scaling will be less aggressive than past roadmap predictions. Already included in 2008 with 3-5 year slow-down. Added another year in 2009.
Ring oscillator delay added to CV/I as more realistic metric (!)
Addition of PMOS saturation current
Subthreshold source-drain leakage currents are held constant
Criterion for source/drain parasitic resistance is set for 33% degradation vs ideal zero series resistance case
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Transistor performance metrics (T. Skotnicki)
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Importance of Drain Induced Barrier Lowering
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DIBL: new performance driver
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Who does better than bulk ? (T. Skotnicki)
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SOI: Why thin buried oxide ?
Avoid drain-to-channel coupling to reduce Short Channel Effects and Drain Induced Barrier Lowering
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Ultra Thin Body and Buried Oxide (UTBB)+ Body bias for tuning
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Can tune to system need !!
Less mismatch in SOI
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Mismatch and SRAM
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CMOS Ultrathin Body and Buried oxide quite some attention (ex
Leti/ST, paper 3.4.4):
Process papers on contact resistance, silicides, etc…
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ALTERNATIVE : FIN FET
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Significant challenges in manufacturing
Parasitics
Body bias more difficult
CMOS & Process Technology sessions CMOS
3: Ultra-thin Body Transistors and Device Variability 10: CMOS Performance Enhancing and Novel Devices 27: Advanced High-k metal Gate SOC and High
Performance CMOS Platforms 34: Advanced FINFETs and Nanowire FETs
Process Technology 2: Advanced 3D Integration 11: Channel Engineering and High-k Technology 18: Advanced Technologies for Ge MOSFETs and New
Concept Devices 26: Advanced Source/Drain and Channel Engineering 33: Novel Process Technologies
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Modeling and Reliability sessions Modeling and Simulation
8: High-Frequency and Multi-Gate Device Modeling 15: Challenges in Advanced Device Performance and
Variation Modeling 22: Simulation of Memory Devices 26: Simulation of Non-Silicon Materials and Devices
Characterization, Reliability and Yield 4: Front End of Line (FEOL) Reliability 28: RTN and Memory 35: Back-end SRAM and ESD Reliability
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Special session: technology and design17: Special Session – Confluence of Technology and Design –
Challenges for Non-Conventional Devices and 3D LSIs Through-chip interface as alternative to
Through Silicon Via (see below) Liquid cooling (EPFL) with regulation Transistors (see above): electrostatics & DIBL, parasitic
capacitance (corner + gate to contact capacitance), design with novel devices (Stanford)
May the fourth (terminal) be with you – circuit design beyond FinFET (AIST Japan), resistive connection to back gate
Variability and self feedback devices (Arizona) Circuits to interface with cells and molecules (Michigan)
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OUTLINE
CMOS
Lithography
Special devices
Metallization
Memories
Displays, Sensors and MEMS
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Lithography (Sivakumar Intel)
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Rayleigh’s Equation
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€
Re solution = k1λ
NA
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Lithography (Sivakumar Intel)
“should maintain k1 above or equal to 0.3 for manufacturability”
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Lithography Sivakumar Intel
Now defect density on par with dry litho
Going to lower k1
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Going to lower k1
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Going to lower k1
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Going to lower k1
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Going to lower k1
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Dual pattern, pitch doubling etc…
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Changing λ -> Extended UV
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Steppers only becoming available now
Need special reflective masks, and need improvement on defect densities
Need at least 2x in light intensity to reach production grade volume
Immature photoresist
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Sivakumar Intel
Ultimately determined by cost
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OUTLINE
CMOS
Lithography
Special devices : emerging technologies
Metallization
Memories
Displays, Sensors and MEMS
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Special devices sessions Quantum, Power and Compound Semiconductor Devices
6: Next Generation Digital Devices 30: Ultra High Speed Transistors
Solid-State and Nanoelectronic Devices 9: CNT, MTJ Devices and Nanowire Photodiodes 16: Low-Power and Steep Slope Switching Devices 23: Graphene Devices
13: Emerging Technologies: Next Generation Power devices and Technology
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Emerging technologies: AlGaN
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Several papers
Example:(30.1)
Record fT
HRL &
JPL laboratories
Emerging technologies: AlGaN
Issue is substrate availability, compatibility with Si if possible is huge advantage
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Samsung GaN epitaxial
films on 4” and 8” Si substrates
Emerging technologies: Ge & III-V
Several papers (like the previous one) on III-V structures and on strained Ge. Contact resistance issue for Ge NMOS
Several papers have been presented on Si substrate. Is an area which receives quite a bit of attention to improve standard CMOS
Walter Snoeys – PH ESE ME – 2011 63
Example 7.4: intel
Emerging technologies : GRAPHENE
Graphene is a 2D system, a single layer of carbon atoms.
Extreme electron mobility (200 000 cm2/Vs) Large hole mobility (~ 1500 cm2/Vs)
Interesting (early development) for fast electronics and fast photo detection
Contact resistance issue
Photon detection: need to create bandgap to reduce leakage, but excellent absorption and carrier transport (examining multilayers)
Walter Snoeys – PH ESE ME – 2011 64
Example:(23.1)
IBM
POWER DEVICES
13: Emerging Technologies: Next Generation Power devices and Technology
Significant production in Si Some special applications
requiring higher performance SiC GaN Not clear yet which one will
win or whether both will stay around
Walter Snoeys – PH ESE ME – 2011 65
Emerging technologies: Integrated photonics
Towards laser Strained Ge on SiDartmouth College & MIT
Optically pumped laser
and LED
Walter Snoeys – PH ESE ME – 2011 66
OUTLINE
CMOS
Lithography
Special devices : emerging technologies
Metallization
Memories
Displays, Sensors and MEMS
Walter Snoeys – PH ESE ME – 2011 67
Metallization towards smaller pitches => need work on parasitics !!!
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Other metallization issues
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Dimension reduction Minimize sidewall/barrier/line edge roughness Intersection of pores with sidewall Patterning, cleaning and filling at nano-
dimensions Seed layers New materials/structures -> integr. complexity Increased number of layers
Thermo-mechanical issues Chemical Mechanical Polishing (CMP) Yield
Reliability Electromigration Stress induced voids Time Dependent Breakdown
Example (session 33.3): leakage between MIMcaps due to metal
penetration in pores
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3D (session 2) TSMC : Nice demonstration of
technology development, but date of full production unclear
IMEC+Japan: stress around via => keep-out zone for transistors
Chinese with IBM Chip fabrication where die can
be individually detached (DE) CEA – Leti – Minatec : various
substrates starting from original SOITEC technology, combined with TSV
Samsung
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Walter Snoeys – PH ESE ME – 2011 73
OUTLINE
CMOS
Lithography
Special devices : emerging technologies
Metallization
Memories
Displays, Sensors and MEMS
Walter Snoeys – PH ESE ME – 2011 74
Memories and Sensors sessions Memory Technology
5: Flash Memory 12: IT Magnetic RAM 19: Resistive RAMs 29: Phase Change Memory and 3-Dimensional Memory
Session 5: example Intel-Micron 64 Gb
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Flash NAND structures
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Work on vertical structures Scaling below 30nm requires significant work on the
transistors
Toshiba 2008
HYNIX
Non-Volatile Memories
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Already in 2007 more NAND and NOR flash memories shipped than DRAM in its entire history (1.9e18)
NVM now ~60 B$ market 80 000 $/GByte in 1987 (256kB unit) to 1.5 $/Gbyte (16Gbyte unit) in 2007 40% price drop per year (ahead of Moore’s learning curve of 30 % per
year) Litho, self-aligning, nand for less space, wafer size increase… Some ‘Partial’ 3D Now new possibility : cross-point memory
Cross-point memory
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Phase Change Memory: heating and then quenching, can be very small, can use Multi-level Cell (need PNV) and Multi-Layer Stacking. Ultimate question is cost.
RRAM: based on simple or more complex oxides which change conductive state, need more work on reliability and understanding of mechanism
IEEE Spectrum dec 2008
Programmable Metallization Cell
Normally in combination with switch, although recently some without
Cross-point memory
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Spin Torque Transfer RAM infinite endurance and high speed
Work to reduce cell size but there are good perspectives (HYNIX 54 nm, Samsung perspectives for 30nm)
Increase cell transistor drive current and reduce magnetic tunnel junction switching current
HYNIX
IBM : yields ok for 64 Mb
OUTLINE
CMOS
Lithography
Special devices
Metallization
Memories
Displays, Sensors and MEMS
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DISPLAYS, SENSORS and MEMS
7: MEMS Resonators: used as frequency references
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Panasonic/IMECQ>200 000 @ 20 MHz
UC Berkeley
DISPLAYS, SENSORS and MEMS 14: Image sensors
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14.3. Single Photon Avalanche
Diode with no afterpulses
(Toyota)
21: Thin Film transistors 31: PV (solar cells) and Energy Harvesting (vibration and
photovoltaic) 36: Biosensors and MEMS
CONCLUSIONS CMOS : according to some (!)
Bulk running out of steam (many tricks already done and now DIBL)
Ultra Thin Body and Buried oxide is good alternative for some time to come
Lithography For 15 nm need advancement on EUV or need to work
with double pattern (in combination with computational lithography). Ultimately a question of cost.
Special devices Intensive work to prepare improvement of MOS, some
things (Ge) already included
Metallization :
need reduced parasitics but porous low k is a challenge
Memories
Displays, Sensors and MEMS
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CONCLUSIONS Metallization
need reduced parasitics but porous low k is a challenge 3D : Some nice examples but timeline for full production
not clear. Some alternatives using capacitive or inductive coupling.
Memories DRAM and NAND in nonvolatile NAND multilevel and vertical structures Crosspoint memory: Phase Change Ram, ReRam,
STTRam as most likely successors
Displays, Sensors and MEMS
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Intel: 22 nm in full production this summerfull RF implemented in 0.32 nm
Walter Snoeys – PH ESE ME – 2011 85
1/f noise improves (Cox dependence)
Semiconductor companies
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Foundries excluded
Significant growth in 2010
Foundries: operating fabrication plants
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Source: wikipedia
More Moore and More Than Moore
Walter Snoeys – PH ESE ME – 2011 88
THANK YOU
Walter Snoeys – PH ESE ME – 2011 89